Abstract

Brain tumours in cetaceans are extremely rare with only four reported cases of intracranial tumors in the scientific literature. Monitoring and recording such cases is crucial as neoplasia may be related to viral, carcinogenic or immunosuppressive chemical exposure and can ultimately contribute to assessing the health of our oceans. A juvenile female, striped dolphin live stranded at Whitepark Bay, Co Antrim, Northern Ireland, UK and died after an unsuccessful attempt at refloatation. At necropsy, a large, soft, non-encapsulated friable mass expanded and replaced the frontal lobes, corpus callosum and caudate nucleus of the brain and extended into the lateral ventricles, displacing the thalamus caudally. Microscopical examination revealed moderately pleomorphic neoplastic cells variably arranged in dense monotonous sheets, irregular streams, true ependymal rosettes and "ependymoblastomatous rosettes." Liquefactive necrosis palisading glial cells, hemorrhage, and mineralization were also frequent. Immunohistochemically, the neoplastic cells labelled positively for vimentin and showed weak, patchy labelling for S100 but were negative for GFAP, cytokeratin, NSE and synaptophysin. Based on these findings a diagnosis of supratentorial primitive neuroectodermal tumor was made.

Acknowledgements

The authors would like to thank Clare Underwood (MRI) and Neil MacIntyre (R(D)SVS) for expert histological preparations. This work was funded by the Northern Ireland Environment Agency and the Scottish Government.

* Presenting author